Table reversing mechanism for grinding machines



[M r 1947. s. E. WOODBURY 2,416,361

TABLE REVERSING MECHANISM FOR GRINDING MACHINES v Filed Nov. 23, 1945 Patented M... 4, 1947 TABLE REVERSING MECHANISM FOR GRINDING MACHINES Stephen E. Woodbury, Beverly, Mass, assignor to Reid Brothers Company, Inc., Beverly, Mass., a corporation of Massachusetts Application November 23, 1945, Serial No. 630,242

8 Claims.

This invention relates to grinding machines and comprises improvements in the table reversing mechanism of such machines. The general objects of the invention are to provide reversing mechanism which shall be simple, compact, reliable in operation, convenient in use, readily adjustable to vary both the path and location of the travel of the work table, and completely guarded so that there is no danger of the operator being caught by moving parts.

Heretofore it has been the practice to provide the work table of grinding machines with a pair of adjustable reversing dogs movable with the table and acting to trip reversing mechanism. Trouble has often been occasioned with the prior construction by the unnoticed loosening of one of the reversing dogs which are subjected to the shock of reversal and thus tend to work loose. The operator, moreover, in moments of inattention is likely to have his hand caught by the moving dogs. These dangers are obviated and important advantages achieved by the mechanism of my invention which is characterized by a longitudinal rock shaft mounted in front of the work table in completely guarded condition, and carrying a pair of longitudinally adjustable cams thereon which cooperate with a cam oscillating element, such as a cam roller carried by the work table. The rock shaft is connected to reversing mechanism. Accordingly, whenever the rock shaft is oscillated by contact of the cam roll with either of the adjustable cams, the reversing mechanism is moved from one position to the other and the path of the table correspondingly terminated and its travel reversed. Other features of the invention relate to the shape and adjustment of the cams, to provision for simultaneously adjusting them, and to means for guarding all moving parts of the mechanism.

These and other features of the invention will be best understood and appreciated from the following description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying drawings, in which:

Fig. 1 is a view in perspective of so much of a grinding machine as is necessary to understand the invention,

Figs. 2, 3 and 4 are fragmentary views of different parts of the mechanism.

The invention is herein shown as embodied in a grinding machine of well-known commercial type including a main frame l and an upright column H in which is mounted a motor-driven grinding wheel l2. Laterally extending ways are formed in the frame ID for a cross slide 13 which is arranged to be adjusted transversely either by 2 hand or automatically in the operation of the machine. The mechanism for adjusting the cross slide is not herein shown since it forms no part of the present invention but is well known to those familiar with the industry,

A work table I4 is mounted for longitudinal reciprocation on the cross slide l3 and is herein shown as equipped with a magnetic chuck IS on which the work may be clamped for travel beneath the grinding wheel l2, The work table is herein shown as provided in its front face with an undercut T-shaped longitudinal groove l6, and in this groove is adjustably mounted a block ll carrying an outwardly projecting cam roll l8. It is not ordinarily necessary to adjust the position of the cam roll 18 in the table l2 after the machine has once been set up, but the illustrated provision for adjustment is a matter of convenience for that purpose.

Attached to the cross slide l3 and adjacent to the front face of the table is a pair of spaced brackets l9 and 20 in which is journaled a rock shaft 21. The shaft 2! is splined throughout its length and carries a pair of double wedge cams 23 and 24 which are keyed to the shaft for longitudinal adjustment and cooperate with the cam roll 18 in rocking the shaft in opposite directions. To this end the two cams are disposed with their operative faces inclined in opposite directions, that is to say, the point of the cam 23 is directed upwardly and the point of the cam 24 is directed downwardly. At its right-hand end the shaft 2| is provided with a crank arm 25 and this, in turn, is connected through a vertical link 26 to an arm 2? on the outer end of a shaft 28 forming a part F of a reversing switch enclosed in the casing 29 secured to the machine frame. The details of the reversing switch are not herein shown since it is a well-known piece of commercial equipment. is sufficient to say that the reversing switch is included in the circuit of an individual motor which drives the work table first in one direction and then in the other. When the shaft Zlis rocked, the reversing switch is thrown from one position to the other, thus terminating the travel of the table in one direction and starting it back in the reverse direction. The construction and arrangement of the reversing motor and switch are disclosed in my prior application Ser. No. 609.522, filed August 8, 1945.

The brackets is and 20 carry a horizontal cover plate 30 which encloses the shaft 2| and the reversing mechanism. Th front plate 31 1s plate 3|.

slidably mounted on supporting blocks 32 and 33 which project forwardly from the brackets l9 and 20. The shaft 2| is retained against longitudinalv mechanism are enclosed in a rectangular casing 36 secured to the right-hand side of the cross slide l3. The front plate 3| is mounted for horizontal adjustment upon the supporting blocks 32 and 33, and for this purpose is provided at its left-hand end with an adjusting screw having a knurled head 31 and being threaded, into the bracket Hi. When this screw is turned, the plate 3] is shifted longitudinally in one direction or the other, and to permit this adjusting movement a guide slot is provided in the casing 36.

It has been explained that the cams 23 and 24 are splined to the rock shaft 2 i. The position of these cams may be individually adjusted and set by flanged slides 38 and 40 in cooperation With the slotted front plate 3]. Each of the cams is provided with a circumferential slot in its hub. In the slot of the cam 24 is received the flange of the slide 38, and in the slot of the cam 23 is received the flange of the slide 40. The slide 33 is provided with a screw having a knurled clamping nut 33, and the slide 40 is provided with a screw having a. knurled clamping nut 4|. The screws project forwardly from their respective slides and carry washers sliding in the slot of the front A guide stud projects outwardly from each flanged slide 38 and 40 adjacent to its screw. The longitudinal slot in the front plate 3| therefore forms a guideway permitting free longitudinal movement of the flanged slides while pre-,

venting angular displacement thereof. It will be understood. that either slide may be clamped in any selected position of adjustment by screwing in its clamping nut against the front plate.

From the foregoing description it will be understood that the clamping screws 39 and 4| may beloosened, and the cams 23 and 24 independently adjusted to the desired limiting positions of the stroke of the work table. They are then clamped in stationary position and the machine will operate with the work table moving in a predetermined path and automatically reversing at each end thereof. Either or both clamping screws may be loosened and reset conveniently to shift the location of the path or its point of reversal at either end. By bodily adjusting the front plate 3| through the medium of the adjusting screw 31, the reversing cams 23 and 24 are longitudinally and simultaneously adjusted, thus shifting the location of the path of the work table while maintaining it constant in extent. In facing the machine the operator has before him only three stationary clamping or adjusting devices, and

these may be conveniently adjusted either While the machine is at rest or while it is in operation and without any possibility of contact with any moving part of the machine.

The reversing cams 23 and 24 are made double wedge in shape for two reasons: in the first place their symmetrical construction permits them to be used in either of the positions required on the shaft 2!. They are simply arranged thereon in opposing positions. In the second place, should the; cam roll 34 be allowed to pass outside the space between the cams, and the cam shaft be turned in the meantime, then the outside wedge face of either cam would serve to turn the shaft back into position. There is, of course, no such 4 safety provision as this in reversing dog mechanisms heretofore known. The axis of the cam roll 34 is located at the same level as the axis of the cam shaft 2 l.

While the reversing mechanism of my invention is shown as embodied in a grinding machine it may be usefully applied to other machine tools having a cutting tool in combination with a reciprocatory table. 7

Having thus disclosed my invention and described in detail an illustrative embodiment thereof, I claim as new and desire to secure by Letters Patent:

1.. A grinding machine having a, grinding wheel and a reciprocatory table carrying a projecting cam roll, a rock shaft disposed parallel to the path of said table, a pair of cams with oppositely inclined operating faces adjustably mounted on said shaft with the said cam roll located between them, and a reversing switch for the table. connected to and operated by said rock. shaft.

2. In a grinding machine equipp d with a grinding wheel, a cross slide and a reciprocatory work table thereon, a rock shaft mounted in the cross slide adjacent to the path of the tabIe a pair of cam-s splined to said shaft and longitudinally adjustable thereon, a cam roll carried by the table and movable into operative engagement with one of said cams after the other, and, a reversing switch connected to the shaft.

3. A grinding machine equipped with a grinding.

wheel, a cross slide and a work table mounted to reciprocate thereon in a path adjacent to the wheel, the said table having a longitudinaly ad;-

justable cam roll projecting from one of its faces, a rock shaft journaled in the cross slide, spaced cams on said shaft located in the path of said cam roll and on opposite sidesthereof, and. a reversing switch connected to said rock shaft.

4. In a grinding machine equipped with. a grinding wheel, a cross slide, and a work table mounted to reciprocate thereon in a. path adjacent to the wheel, the said table having an adjustably mounted cam roll projecting from its front face, a rock shaft mounted on the cross slide adjacent to the front face of the table, a pair of cams splined to the shaft on opposite sides of the said cam roll, means for adjustably clamping said cams in any selected positions on said shaft, means for simultaneously adjusting both cams together, and. a reversing switch operatively connected to the said shaft.

5. In a grinding machine or the like, a reciprocatory table carrying a forwardly projecting cam roll, a stationary shaft disposed longitudi nally in front, of the said table with its axis at substantially the same level as the axis of the cam roll, a pair of double wedge cams splined tov said shaft, 3], flanged slide connected to each cam, clamping means carried by each slide, and a re- Versing switch operated by oscillation of said shaft.

6. In a grinding machine or the like, are ciprocatory table, a stationary guard plate located in front of the table, a longitudinal rock-shaft journaled between the table and guard plate, reversing mechanism operated by the rock-shaft, a cam oscillating element carried. by the table andmovable ina path, adjacent to the. rock-shaft, spaced cams splined to the rock-shaft and arranged to cooperate with said oscillating element, and normally stationary clamping devicesasso ciatedwith the guard plate for adjustably determining the setting of said cams.

7. In a grinding machine or the like, a reciprocatory table carrying a projecting cam roll, a stationary guard plate located in front of the table and spaced therefrom'to permit free movement of the cam roll with the table, a longitudinal rock-shaft journaled between the table and the guard plate, a reversing mechanism for the table connected to the rock-shaft, a pair of double wedge cams splined to said shaft on opposite sides of the cam roll, normally stationary clamping devices associated with the guard plate and being connected to the cam rolls to hold them independently in longitudinally adjusted position upon the rock-shaft and at the same time permitting oscillatory movement thereof with said shaft, and means for longitudinally adjusting the guard plate together with said clamping devices and the said cams.

8. A grinding machine equipped with a grinding wheel, a cross slide and a work table mounted to reciprocate thereon in a path adjacent to the grinding wheel, supporting members fastened to the cross slide in front of the work table, a rock shaft journaled in said supporting members to rock about an axis parallel to the path of the reciprocatory work table, cooperating means on the work table and shaft for rocking the shaft in opposite directions at predetermined points in the travel of the table, and a reversing switch operatively connected to said shaft.

STEPHEN E. WOODBURY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Huxford et al July 5, 1932 Hanson Nov. 11, 1924 Hanson Mar. 6, 1923 Hanson Feb. 5, 1918 Number 

